Reactivity of Biogenic Volatile Organic Compound Emissions and Their Attribution to Identified Chemical Species

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

This project will investigate the missing reactivity that has been reported in a number of recent studies of biogenic volatile organic compound (BVOC) emissions in the forest atmosphere. It centers on the application of a new approach for the direct determination of the ozone reactivity of BVOC emissions from vegetation. Air drawn from enclosures containing vegetation will be mixed with ozone-enriched air and then passed through a flow tube where the loss of ozone will be measured directly with a differential ozone monitor. Ozone reactivity will be determined for BVOC emissions from a range of vegetation types in the National Center for Atmospheric Research (NCAR) greenhouse, at a local tree nursery in Boulder, CO, at the University of Michigan Biological Station (UMBS), and at the Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics & Nitrogen (BEACHEON) Manitou Forest research site. These vegetation types include the dominant species in U.S. forests. Ozone and OH reactivity experiments conducted in parallel will shed light on how the missing reactivity of these oxidants varies with species, with environmental condition, and relative to each other, thereby providing insight regarding the identities of unknown compounds. The applicability of BVOC + O3 rate constants for estimating the corresponding rates of ozone removal will be evaluated based on kinetic laboratory experiments. Results of the project will help improve photochemical models of radical chemistry in the forest atmosphere. The project will also support continued operation of CU's capillary diffusions system for generating sesquiterpene standards that are used by the PIs' groups as well as other research groups in the community. The development and evaluation of this new measurement approach has potentially wide-ranging applications for both reevaluating results from past experiments and planning and characterizing BVOC reactivity during future campaigns. This project will contribute to the education of undergraduate students and a postdoctoral researcher. Students from minorities will be recruited from the SOARS and SMART programs to help with the summer field work. The broader public will benefit from presentation of this work to 8th graders at INSTAAR's Annual Open House, through a booth planned at the 2012 Boulder Creek Festival, through a dedicated web portal, and through interactions with the City of Denver "The Mile High Million" program. A better understanding of BVOC chemistry will lead to more effective air pollution mitigation strategies resulting in improved air quality and health.